三十二,对象序列化
1.对象序列化定义
将一个对象保存为二进制的数据流.一个对象要想序列化,必须实现Serializable接口.此接口没有任何方法,只是一个标识接口,类似的还有Clonable接口.
一个对象要序列化还需要依靠ObjectOutputStream类和ObjectInputStream类.
2.对象序列化
序列化类示例:
package com.ares.serdemo;
import java.io.Serializable;
public class Person implements Serializable {
private String name;
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String toString() {
return "姓名：" + this.name + "，年龄：" + this.age;
}
}
示例:
package com.ares.serdemo;
import java.io.File;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
public class ObjectOutputStreamDemo {
public static void main(String[] args) throws Exception {
File file = new File("d:" + File.separator + "person.ser");
ObjectOutputStream oos = null;
oos = new ObjectOutputStream(new FileOutputStream(file));
Person per = new Person("张三", 30);
oos.writeObject(per) ;
oos.close() ;
}
}
3.反序列化
示例:
package com.ares.serdemo;
import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectInputStream;
public class ObjectInputStreamDemo {
public static void main(String[] args) throws Exception {
File file = new File("d:" + File.separator + "person.ser");
ObjectInputStream ois = null;
ois = new ObjectInputStream(new FileInputStream(file));
Object obj = ois.readObject();
Person per = (Person) obj;
//向下转型
System.out.println(per);
}
}
备注:如果类中的某个属性不希望被序列化,则可以使用transient关键字申明.
4.一组对象的序列化
示例:
package com.ares.serdemo;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class ArraySerDemo {
public static void main(String[] args) throws Exception {
Person per[] = { new Person("张三", 30), new Person("李四", 31),
new Person("王五", 32) };
ser(per);
Person p[] = (Person[]) dser();
print(p) ;
}
public static void ser(Object obj) throws Exception {
File file = new File("d:" + File.separator + "person.ser");
ObjectOutputStream oos = null;
oos = new ObjectOutputStream(new FileOutputStream(file));
oos.writeObject(obj);
oos.close();
}
public static Object dser() throws Exception {
Object temp = null;
File file = new File("d:" + File.separator + "person.ser");
ObjectInputStream ois = null;
ois = new ObjectInputStream(new FileInputStream(file));
temp = ois.readObject();
return temp;
}
public static void print(Person per[]) {
for (Person p : per) {
System.out.println(p);
}
}
}
5.序列化完成单人信息的增删改查操作
示例:
菜单代码:
package com.ares.persondemo;
public class Menu { // 显示菜单
public Menu() {
while (true) {
this.show();
}
}
public void show() {
System.out.println("====== Xxx 系统 ========");
System.out.println(" [1]、增加数据 ");
System.out.println(" [2]、查看数据 ");
System.out.println(" [3]、修改数据 ");
System.out.println(" [4]、删除数据 ");
System.out.println(" [0]、退出系统 ");
InputData input = new InputData();
int choose = input.getInt("\n\n请选择：", "输入错误，重新输入，");
switch (choose) {
case 1: {
Operate.add();
break;
}
case 2: {
Operate.find();
break;
}
case 3: {
Operate.update();
break;
}
case 4: {
Operate.delete();
break;
}
case 0: {
System.exit(1);
}
default: {
System.out.println("无效的选项");
}
}
}
}
FileOperator代码:
package com.ares.persondemo;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
public class FileOperate {
private File file = null;
public FileOperate(String path) {
this.file = new File(path); // 从外部指定操作的文件路径
}
public void save(Object obj) throws Exception {
ObjectOutputStream oos = null;
oos = new ObjectOutputStream(new FileOutputStream(file));
oos.writeObject(obj);
oos.close();
}
public Object load() throws Exception {
Object temp = null;
ObjectInputStream ois = null;
ois = new ObjectInputStream(new FileInputStream(file));
temp = ois.readObject();
return temp;
}
}
Operate代码:
package com.ares.persondemo;
public class Operate {
public static void add() {
InputData input = new InputData();
String name = input.getString("输入姓名：");
int age = input.getInt("输入年龄：", "输入的不是数字，");
Person per = new Person(name, age);
FileOperate operate = new FileOperate("d:\\pers.ser");
try {
operate.save(per);
} catch (Exception e) {
e.printStackTrace();
}
}
public static void find() {
FileOperate operate = new FileOperate("d:\\pers.ser");
Person per = null;
try {
per = (Person) operate.load();
} catch (Exception e) {
e.printStackTrace();
}
if (per != null) {
System.out.println(per);
} else {
System.out.println("没有任何的数据。");
}
}
public static void update() {
//修改对象的属性
FileOperate operate = new FileOperate("d:\\pers.ser");
Person per = null;
try {
per = (Person) operate.load();
} catch (Exception e) {
e.printStackTrace();
}
InputData input = new InputData();
String name = input.getString("输入姓名（原姓名：" + per.getName() + "）：");
int age = input.getInt("输入年龄（原年龄：" + per.getAge() + "）：", "输入的不是数字，");
per = new Person(name, age);
operate = new FileOperate("d:\\pers.ser");
try {
operate.save(per);
} catch (Exception e) {
e.printStackTrace();
}
}
public static void delete() {
FileOperate operate = new FileOperate("d:\\pers.ser");
try {
operate.save(null);
} catch (Exception e) {
e.printStackTrace();
}
}
}
Person类代码:
package com.ares.persondemo;
import java.io.Serializable;
public class Person implements Serializable {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
private int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public String toString() {
return "姓名：" + this.name + "，年龄：" + this.age;
}
}
Test类代码:
package com.ares.persondemo;
public class TestMenu { // 显示菜单
public static void main(String args[]) {
new Menu();
}
}
6.投票系统示例
示例:
Menu类代码:
package com.ares.demo;
// 循环选择\修改选票\显示全部的信息
public class Menu {
private Student stu[] = { new Student(1, "张三", 0), new Student(2, "李四", 1),
new Student(3, "王五", 0), new Student(4, "刘六", 0) };
public Menu() {
Operate oper = new Operate(stu);
// 1、显示出全部的数据
oper.list();
// 2、调用投票
while (oper.vote()) {
;
}
// 3、列出全部的票数
oper.list();
// 4、求出结果
oper.result() ;
}
}
Student类:
package com.ares.demo;
public class Student implements Comparable<Student> {
//实现Comparable接口
private int stuno;
private String name;
private int count;
public Student() {
super();
}
public Student(int stuno, String name, int count) {
super();
this.stuno = stuno;
this.name = name;
this.count = count;
}
public int getStuno() {
return stuno;
}
public void setStuno(int stuno) {
this.stuno = stuno;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getCount() {
return count;
}
public void setCount(int count) {
this.count = count;
}
public int compareTo(Student stu) {
//覆写比较方法
if (this.count > stu.count) {
return -1;
} else if (this.count < stu.count) {
return 1;
} else {
return 0;
}
}
}
Operate类代码:
package com.ares.demo;
public class Operate {
private Student stu[] = null;
private InputData input = null;
public Operate(Student stu[]) {
this.stu = stu;// 对象数组的内容由外部决定
this.input = new InputData();
}
public void list() {
for (int i = 0; i < this.stu.length; i++) {
System.out.println(this.stu[i].getStuno() + "："
+ this.stu[i].getName() + "【" + this.stu[i].getCount()
+ "票】");
}
}
public boolean vote() {// 完成具体的投票功能
boolean flag = true;
int stuno = this.input.getInt("请输入班长候选人代号（数字0结束）：",
"此选票无效，请输入正确的候选人代号！");
switch (stuno) {
case 1: {
this.stu[0].setCount(this.stu[0].getCount() + 1);// 修改选票
break;
}
case 2: {
this.stu[1].setCount(this.stu[1].getCount() + 1);// 修改选票
break;
}
case 3: {
this.stu[2].setCount(this.stu[2].getCount() + 1);// 修改选票
break;
}
case 4: {
this.stu[3].setCount(this.stu[3].getCount() + 1);// 修改选票
break;
}
case 0: {
flag = false;
break;
}
default: {
System.out.println("此选票无效，请输入正确的候选人代号！");
}
}
return flag;
}
public void result() {
java.util.Arrays.sort(this.stu);// 对象数组排序
System.out.println("投票最终结果：" + this.stu[0].getName() + "同学，最后以"
+ this.stu[0].getCount() + "票当选班长！");
}
}
InputData类代码:
package com.ares.demo;
//可以作为一个工具类保存.
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
public class InputData {
private BufferedReader buf = null;
public InputData() {
this.buf = new BufferedReader(new InputStreamReader(System.in));
}
public String getString(String info) {
String str = null;
System.out.print(info);// 打印提示信息
try {
str = this.buf.readLine();
} catch (IOException e) {
e.printStackTrace();
}
return str;
}
public int getInt(String info, String err) {
int temp = 0;
boolean flag = true;// 定义一个标志位
while (flag) {
String str = this.getString(info);
if (str.matches("\\d+")) {
temp = Integer.parseInt(str);
flag = false;// 退出循环
} else {
System.out.print(err);
}
}
return temp;
}
public float getFloat(String info, String err) {
float temp = 0.0f;
boolean flag = true;// 定义一个标志位
while (flag) {
String str = this.getString(info);
if (str.matches("\\d+.?\\d+")) {
temp = Float.parseFloat(str);
flag = false;// 退出循环
} else {
System.out.print(err);
}
}
return temp;
}
public char getChar(String info, String err) {
char temp = ' ';
boolean flag = true;// 定义一个标志位
while (flag) {
String str = this.getString(info);
if (str.matches("\\w")) {
temp = str.charAt(0);
flag = false;// 退出循环
} else {
System.out.print(err);
}
}
return temp;
}
public Date getDate(String info, String err) {
Date temp = null ;
boolean flag = true;// 定义一个标志位
while (flag) {
String str = this.getString(info);
if (str.matches("\\d{4}-\\d{2}-\\d{2}")) {
try {
temp = new SimpleDateFormat("yyyy-MM-dd").parse(str) ;
} catch (ParseException e) {
System.out.print(err) ;
}
flag = false;// 退出循环
} else {
System.out.print(err);
}
}
return temp;
}
}
Test类代码:
package com.ares.demo;
public class Test {
public static void main(String[] args) {
new Menu();
}
}
20150512
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